1. Field of the Invention
The present invention relates to a stencil printing machine. The stencil printing machine of the present invention includes a stencil sheet and a pressure chamber for storing the stencil sheet and a printing sheet. Pressure reducing means is connected to the pressure chamber for reducing pressure inside the pressure chamber. A part of wall-structure of a the pressure chamber is composed of a flexible sheet material. When the pressure reducing means reduces pressure inside the pressure chamber, atmospheric pressure exerts on ink via the flexible sheet material. The ink is transferred to the printing sheet through perforations of the stencil sheet, thereby conducting printing.
2. Description of the Related Art
In Japanese Laid Open Publication No. 6-270523, the present applicant has been proposed a basic concept of a pressure type stencil printing machine that is provided with such a pressure chamber. The stencil printing machine is provided with a pressure chamber, and a wall-structure which is partly composed of a flexible diaphragm device. To the pressure chamber, pressure reducing means is connected. The pressure type stencil printing machine is capable of conducting stencil printing easily and quickly at a predetermined and constant printing-density even in the case where a printing area is large.
In such stencil printing machine, however, the pressure chamber is inevitably enlarged and pressure reducing means of a large capacity is required if the machine is applied to a large printing area. Such pressure reducing means of a large capacity may be a vacuum pump, especially one provided with a motor blower. In the case where such pressure reducing means is adopted, following problems arise. Firstly, the whole of the printing machine is large. Further, much time is consumed until printing pressure reaches an appropriate level for printing since the pressure reduction is conducted at a constant speed. Further, a fine control of the printing pressure is difficult to be conducted. Much operating time is required and the operation is complicated.
An object of the present invention is to provide a stencil printing machine using the above-mentioned pressure reduction, wherein the pressure reduction can be easily and rapidly conducted, the whole machine is small, light and simple, and further operational convenience is improved.